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How much further can I overclock here?

Hi All,

Well, I got my Phenom 995Z (125W version of the 9950) up to 3.0Ghz, but it was only stable beyond the 1.3V and 61C maximums listed in the processor spec (I had to run it at 1.375V and this produced a core temp around 62 to 63 C under max load.) I used AMD Overdrive, speedfan, and cputemp to get the core voltage and temps. Since then I'm running it at 2.939Ghz and dropped the voltage so I am within spec now. The weird thing is the 9950 has a max limit of 64C, but the 995Z has 61C as its limit. Why? Is it just because of the Wattage decrease?

Does water cooling drop the core temp by any reasonable amount? I know it would drop the motherboard sensor temp, just not sure on the core itself.

Also, I see people saying they got 3.3Ghz @ 1.65V. I know that kills the warranty, but just how much thermal overload and over voltage can I reasonably expect the Phenom architecture to take before I have a puddle of molten silicon on the bottom of the case? Or more directly, I know the warranty is 3 years, which under normal operating conditions (below 1.3V and below 61C) will keep my processor in fine shape. But how far beyond the "limits" that AMD has stipulated can I go safely on the stock cooler? I've seen 1.45V on stock air cooling listed elsewhere but what about thermal limits?

I guess I'm asking is how "extreme" I can go with this processor before I "exterminate" it?

Sorry if I'm rambling a bit here, but I'd like to know how much further I can proceed with my overclocking.

Mike Doerner

PS I'm running on an ASUS M3A78-T w/ 790GX chipset, if that matters. And 4Gb of Corsair DDR-2 1066 ram.

Stock cooler? You don't overclock on a stock cooler. If money is a concern, get something like a Xigmatek S1284 for 35 bucks. Maybe also a tube of Arctic Silver 5 for 3 bucks. This will get your temps at least 10C lower than what you have now. (I dropped from 60C to 47C at full load.)

Are your temps lower on the core, or the motherboard sensor? Yea, I'm on the stock cooler with Arctic Silver's Ceramique. I would probably have to swiss cheese my case then to get more air, as I only have one fan besides the PSU fan.

The stock cooler from AMD I heard was adequate for overclocking (or so i thought.) On another forum, a water cooler guy only had a 2C drop compared to his air cooled setup on the stock cooler.

I guess I'm skeptical on an aftermarket cooler on reducing the CORE temp.

Are your temps lower on the core, or the motherboard sensor? Yea, I'm on the stock cooler with Arctic Silver's Ceramique. I would probably have to swiss cheese my case then to get more air, as I only have one fan besides the PSU fan.

The stock cooler from AMD I heard was adequate for overclocking (or so i thought.) On another forum, a water cooler guy only had a 2C drop compared to his air cooled setup on the stock cooler.

I guess I'm skeptical on an aftermarket cooler on reducing the CORE temp.

Mike Doerner

Well there are a couple of things here. First of all, never trust internal sensors for temp values. This is especially the case when dealing with phenoms. The phenoms reports a temperature value that is relative to a certain predefined value, it doesn't report the actual processor temperature so take that into consideration as it's very unlikely that the temp rating your getting is accurate but should be useful enough to measure the temp drop by using a aftermarket HSF.

Second, yes by all means get a aftermarket cooler. My recommendation is the Thermalright 120 Extreme if you want to do some day-in/day-out overclock. Just upgrading to one of them can mean a huge drop of 10C+ temps over the factory cooler. On my 9850 the temp drop was 11C when under full load over the factory cooler when exchanged for a 120. Temp readings using the onboard sensors said the proc was running @ 63 C but by using an external probe it was actually @ 48C under full load OC'd at 3.2 Ghz and a voltage of 1.4 and my fan on the heatsink running at a paultry 600 RPM resulting in a good OC and still quiet system.

The reason I recommend the Xigmatek cooler is because the heatpipes are in direct contact with the CPU.

And it's cheaper than the really overpriced Thermalright

But both do an excellent job. Anyway, there are a LOT of reviews out there for those (and other) coolers. Read and pick what you like. Fact is though, that the stock cooler is good for what it is: a stock cooler. If you gonna OC, you need a cooler with heatpipe technology, period. 4 heatpipes minimum for direct contact coolers, 6 heatpipes minimum for normal ones.

The reason I recommend the Xigmatek cooler is because the heatpipes are in direct contact with the CPU.

And it's cheaper than the really overpriced Thermalright

But both do an excellent job. Anyway, there are a LOT of reviews out there for those (and other) coolers. Read and pick what you like. Fact is though, that the stock cooler is good for what it is: a stock cooler. If you gonna OC, you need a cooler with heatpipe technology, period. 4 heatpipes minimum for direct contact coolers, 6 heatpipes minimum for normal ones.

The Xigmatek has a few flaws. First of all the entire heatspreader of the CPU does not get covered by it which deteriorates the direct contact advantage. Second the retention bracket for the AM2 sockets is extremely poor and flimsy by only utilizing the middle tabs on the stock HSF clip. That's a pretty heavy HSF to be relying on two little tabs when the MB is put into a tower case. Plus the Xigmatek does not allow for a secondary fan to be placed on it as it provides no way of easily clipping another fan onto it. Under full load in a OC'd use the Thermalright has a significant advantage where the Xigmatek starts loosing steam and the Thermalright also starts pulling away by an even greater margin after lapping the base and proc.

"But taken in consideration that this is a pre-production sample, that the performance should be better when it hits the market and that the price of the Xigmatek Achilles S1284 gives you very good price/performance that cannot be mached by any other in the market."

I do have this Xigmatek (among other aftermarkets). It performs very, very good. I also wonder why on earth would I pay the high price of the TT 120 if I have to do lapping, lol?

The cooler has a very high performance-to-cost ratio.

Btw, I have this on my Intel PC, not the AMD one. But that shouldn't matter much. As of its weight, it's actually very light. Lighter than the stock cooler even.

Of course if you've got money to burn, buy the 120 for 2 or 3 degrees C lower temps (and spend a day lapping it because Thermalright wants to cut costs for an actually expensive cooler, meh...)

I also have the Xigmatech, and I can tell you first hand that the Thermalright does perform better then it by a good margin even without lapping. That's why the Xigmatech has been since slapped in a less demanding system where the mount and OC performance does not play a big factor, in my HTPC.

Just in case you didn't know: The Xigmatek is prone to perform worse when the orientation is changes. The pipes can run parallel or across the CPU depending on the orientation in which you mounted it. For Intel CPUs, you can rotate it by 90 degrees clockwise or counterclockwise.

For AMDs, probably not unless you use a backplate to mount it :P

This is only important on dual cores though. Quad cores are placed symmetrically inside the CPU case.

Most online reviews of the cooler show temps that are only about 3 degrees worse than the 120 (and in a few cases, better).

The problem is it's not clear whether there's a difference between AMD and Intel CPUs. On Intel, you can go 3.8GHz with it easily with a CPU that runs 2.4GHz stock (tested on E6600).

know the warranty is 3 years

I know that kills the warranty, but just how much thermal overload and over voltage can I reasonably expect the Phenom architecture to take before I have a puddle of molten silicon on the bottom of the case? Or more directly, I know the warranty is 3 years, which under normal operating conditions (below 1.3V and below 61C) will keep my processor in fine shape. But how far beyond the "limits" that AMD has stipulated can I go safely on the stock cooler? I've seen 1.45V on stock air cooling listed elsewhere but what about thermal limits.